The calendar has flipped to June, meaning the All-Star break sits roughly a month away and the trade deadline lands in exactly two months. This is the meat of the baseball season—the stretch where contenders separate themselves from pretenders, and where teams finally get a clear picture of what they actually have.
For the Seattle Mariners, what they have is a surplus. After opening the year 8-13, they now sit atop the AL West with baseball's sixth-best record since that sluggish start. Josh Naylor and Julio Rodríguez have started generating offense, and top prospect Colt Emerson gave the lineup a needed boost after his call-up. The Mariners are beginning to resemble the team many expected them to be.
Now comes a problem—quoted because most teams would happily trade for it—Seattle suddenly has too many good starting pitchers.
A Six-Man Rotation Logsjam
Emerson Hancock's emergence, complete with a 2.80 ERA and underlying numbers that look even better, gives the Mariners six viable starters: Luis Castillo, Logan Gilbert, George Kirby, Bryce Miller, Bryan Woo, and Hancock himself. That's six deep, which is the kind of depth that makes general managers sleep better at night.
Miller's oblique injury in spring training cracked open the door for Hancock to claim arotation spot. When Miller returned on May 13, the Mariners faced a decision: send someone to the minors or roll with a six-man rotation. Instead, they tried something different—a piggyback system pairing Castillo and Miller together.
Castillo had struggled to a 6.57 ERA through his first eight starts. By using him alongside Miller, the Mariners could smooth out those rough edges while keeping both arms stretched out. In three rotation turns, the pair worked 27 of 28 possible innings, Seattle won two of three games, and they posted a combined 1.67 ERA.
The setup wasn't without friction. Castillo had never made a relief appearance before—his May 19 start marked his 253rd career game and first time coming out of the bullpen. After a May 25 game, Castillo was spotted slamming his glove in the dugout and engage in a lengthy conversation with manager Dan Wilson. Wilson, along with POBO Jerry Dipoto, met with both pitchers to explain the reasoning and smooth things over.
"This is not an easy science, the piggyback thing," Wilson said after that game. "You're weighing a lot of different things. And a tough decision in terms of pulling Castillo, and I think he just continues to prove to be an incredibly selfless player."
Both pitchers ultimately put team success ahead of personal preference. The tandem delivered when it mattered, giving the bullpen a night off every fifth day while staying ready for traditional starts.
The Schedule Forces a Change
Starting Friday, the Mariners face 10 games in 10 days followed by 16 games in 17 days. That grueling stretch ends the piggyback experiment—at least for now. Seattle switches to a six-man rotation, giving every starter extra rest while keeping Castillo and Miller working as conventional starting pitchers.
Given how well the piggyback worked, don't be surprised to see it return later in the season. Wilson acknowledged the gambit this past weekend: "You've got to tip your cap to them. Their willingness to put the team first in these situations—both of these guys deserve a huge pat on the back for the way they've approached it."